1. Field of the Invention
The present invention relates to a method of scheduling in wireless packet communication system, and more particularly, to a method of scheduling uplink packets in wireless communication system. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for transmitting scheduling information to specified groups of subscribers or to all subscribers.
2. Discussion of the Related Art
With increasing demand in speed and size of uplink transmission, methods of high-speed packet communication during the uplink from a mobile device to a base station are widely being discussed. E-DCH (Enhanced uplink Dedicated CHannel) of 3GPP WCDMA (3rd Generation Partnership Project, Wideband Code Division Multiple Access) is an example of one of the methods being discussed.
The E-DCH incorporates existing methods such as uplink packet scheduling from Node B (base station) in the 3GPP WCDMA uplink DCH (Dedicated CHannel) and HARQ (Hybrid Automatic Retransmission reQuest) in the Physical Layer (PHY) to increase the efficiency of uplink transmission. Through efficient construction of scheduling assignment from Node B, the system processing rate is increased.
Node B controlled scheduling is one of the methods that is applicable to the existing 3GPP WCDMA E-DCH. According to current discussions on standards, techniques such as Time Division Multiplex (TDM), Code Division Multiplex (CDM), or time and code division multiplex can be used to transmit Node B scheduling assignment (Similar to High Speed Downlink Packet Access (USDPA)). If any of the three techniques are used, scheduling assignment transmitted to each user equipment (UE) contains at least UE classification identification (UE ID) and the contents of scheduling assignment.
Each UE inspects the downlink channel which is used to transmit scheduling assignment via UE ID. If the UE ascertains that the scheduling assignment transmitted as a part of UE ID is correctly addressed, the UE acquires the contents of the scheduling assignment. According to the scheduling assignment, the UE starts, terminates, or holds transmission. Since the scheduling assignment is transmitted from Node B to each UE, a substantial amount of time is required to transmit the same scheduling assignment to a specified group of UEs or to all the UEs.
As discussed above, scheduling assignments are independently transmitted using time division, code division, or time-code division techniques to each UE. Consequently, a problem arises in transmitting scheduling assignments to a specified group(s) of UEs or to all the UEs in the PHY. In addition, transmitting using such techniques to individual UE causes traffic congestion due to sudden increase in uplink traffic in the PHY and cannot be dealt with quickly.